The United Nations' envoy for Syria has warned that Syrian armed forces could launch a new offensive to crush resistance in eastern Aleppo before Donald Trump formally assumes the U.S. presidency on January 20.

Staffan De Mistura joined German Foreign Minister Frank-Walter Steinmeier on November 23 in calling for an end to the bombardment in Syria, and in Aleppo in particular.

Some European diplomats have said Syrian President Bashar al-Assad may feel emboldened by Trump's vow to build closer ties with Russia, and this may see Damascus push for a crucial victory in Aleppo.

The city has been devastated, and is the focus of some of the worst fighting of the six-year civil war.